Directions: Use the information below to help you fill in the chart provided. This information is a summary of Chapter 12, Sects 1-4.
WAVE EROSION
How Do Waves Form?
The power of oceanic waves is awesome! Large storm waves can produce 2000 pounds of pressure per square foot. The pure energy of waves along with the chemical content of the water is what erodes the rock of many coastlines. Waves form when wind blows over the surface of the ocean. Strong winds produce large waves. The wavesmove toward land. When waves crash into the land over along time, they can break rock down into smaller pieces. These pieces are called sand. A shorelineis a place where the land and the watermeet. Most shorelines contain sand. The motion of waveshelps to shape shorelines. During erosion, waves removesand from shorelines.
What Are the Effects of Wave Erosion?
The energy in waves is constantly breaking rock intosmaller and smaller pieces. Crashing waves can breaksolid rock and throw the pieces back toward the shore. Breaking waves can enter cracks in the rock and breakoff large boulders. Waves also pick up fine grains of sand. The loose sand wears down other rocks on the shorethrough abrasion.
Wave erosion can produce many features along a shoreline. For example, sea cliffs form when waves erode rock to form steep slopes. As waves strike the bottom ofthe cliffs, the waves wear away soil and rock and make the cliffs steeper. Sea cliffs made of hard rock, such as granite, erode very slowly. Sea cliffs made of soft rock, such as shale, erode more rapidly, especially during storms.
WIND EROSION
How Does Wind Form?
Wind is caused by air flowing from high pressure to low pressure.
What Are The Effects of Wind Erosion?
Wind can move soil, sand, and small pieces of rock. Therefore, wind can cause erosion. However, some areasare more likely to have wind erosion than other areas. For example, plant roots help to hold soil and rock inplace. Therefore, areas with few plants, such as deserts
and coastlines, are more likely to be eroded by wind. These areas also may be made of small, loose rock particles. Wind can move these particles easily.
Wind moves material in three different ways. In areas where strong winds occur, material is moved by saltation. Saltationis the skipping and bouncing movement of sand-sized particles inthe direction the wind is blowing. When moving sand grains knock into one another, some grains bounce up in the air, fall forward, and strike other sand grains. These impacts
cause other grains to roll and bounce forward. Another way that wind can move material is by deflation. The removal of fine sediment by wind is called deflation. During deflation, wind removes the top layer of fine sediment or soil and leaves behind rock fragments that are too heavy to be lifted by the wind. The last way that wind can erode material is by abrasion. The grinding and wearing down of rock surfaces by other rock or sand particles is called abrasion. Abrasion commonly happens in areas where there are strong winds, loose sand, and soft rocks. The blowing of millions of sharp sand grains creates a sandblasting effect. This effect helps to erode, smooth, and polish rocks.
ICE EROSION (GLACIERS)
How Do Glaciers Form?
A glacier is an enormous mass of moving ice. Because glaciers are very heavy and have the ability to move across the Earth’s surface, they are capable of eroding, moving, and depositing large amounts of rock materials. Glaciers form in areas so cold that snow stays on the ground year-round. In polar regions and at high elevations, snow piles up year after year. Over time, the weight of the snow on top causes the deep-packed snow to become ice crystals. These ice crystals eventually form a giant ice mass. Because glaciers are so massive, the pull of gravity causes them to flow slowly, like “rivers of ice.”
What Are The Effects of Glacial/Ice Erosion?
Continental glaciers and alpine glaciers produce landscapes that are very different from one another. Continental glaciers smooth the landscape by scraping and eroding features that existed before the ice appeared. Alpine glaciers carve out rugged features in the mountain rocks through which they flow, such as those in the Rocky Mountains and the Alps.
EROSION BY GRAVITY (MASS MOVEMENT)
Although you can’t see it, the force of gravity is also an agent of erosion. Gravity not only influences the movement of water and ice but also causes rocks and soil to move down slope. Mass movement is the movement of any material, such as rock, soil, or snow, down slope. Whether mass movement happens rapidly or slowly, it plays a major role in shaping the Earth’s surface.
What Are The Effects of Gravity (Mass Movement) Erosion?
The most destructive mass movements happen suddenly and rapidly. Rapid mass movement can be very dangerous and can destroy everything in its path. Sometimes, you don’t even notice mass movement happening. Although rapid mass movements are visible and dramatic, slow mass movements happen a little at a time. However, because slow mass movements occur more frequently, more material is moved collectively over time.